Colorado Criminal Lawyer BlogA Threat To The “Coached Victim” Defense Theory In Colorado Sex Assault Cases
A Threat To The “Coached Victim” Defense Theory In Colorado Sex Assault Cases
By H. Michael Steinberg, Colorado Criminal Defense Lawyer
Introduction
In the 2026 Colorado Supreme Court child sexual assault ruling of Gustavo LOPEZ, Petitioner, v. The PEOPLE of the State of Colorado, the defense asserted the very common and often successful defense of victim or witness coaching.
The Colorado Supreme Court issued a 4–3 decision addressing the admissibility of expert testimony in child sex abuse cases where the defense theory of the case was witness coaching.
The majority of the Colorado Supreme Court acknowledged that the prosecution’s expert testimony technically amounted to improper vouching. However, the court upheld the conviction under the so-called “opening the door” doctrine, reasoning that, because the defense had repeatedly introduced evidence and arguments suggesting the children were coached, the defense had opened the door for the prosecution to directly respond through its expert witness.
The Facts Of The Lopez Case
Gustavo Lopez was tried in Boulder County (2019) on charges of child sexual assault involving three young relatives. There was no forensic evidence in the case, and the victim’s testimony was somewhat contradictory. The defense focused on a theory that the alleged victims were coached by a relative. Specifically, the defense essentially argued that the children had been coached by their maternal grandmother to fabricate the allegations as part of a custody dispute.
During the trial, the prosecution, in response to the defense of victim “coaching,” called forensic interviewer Kim Grimm, who testified that she did not see any “huge red flags” indicating that the children had been coached.
Lopez was convicted and appealed. The issue on appeal addressed two key Colorado evidence rules (CRE 608(a) and 702). Those important rules generally bar experts from directly vouching for a witness’s truthfulness. That is, an expert who offers an opinion to the jury that a witness is or isn’t being honest is the jury’s province, not the proper subject of an expert’s opinion.
In my opinion, one of the key foundations of our criminal justice system is that juries assess the credibility of witnesses.
Lopez argued the interviewer’s “no signs of coaching” testimony crossed that critical line in the sand.
The Importance Of The Dissent In The Lopez Decision
The case was very closely decided, with the dissent making clear that the majority would ultimately regret their position.
Chief Justice Monica Márquez joined by Justices Boatright and Blanco, warned that the majority decision effectively “guts” coaching defenses in child sex abuse cases going forward, since defendants who raise coaching can now expect an expert to directly rebut them on credibility cutting into the juries province.
The dissent reasoned and cautioned that this ruling could significantly undermine coaching defenses in future child sex abuse cases, as raising the issue may now permit the prosecution to have an expert directly rebut credibility challenges.
How Will This Impact Future Trials In Colorado Sexual Assault On Children Cases?
Defense strategies for child sexual assault charges in Colorado will clearly be impacted.
This is a significant evidence-law ruling for Colorado criminal practice, particularly in child sexual assault prosecutions. The case gives prosecutors a route to introduce expert “no coaching indicators” testimony — testimony that would normally be excluded as improper vouching — whenever the defense leans on a coaching theory.
Defense attorneys will need to be much more careful about how they raise allegations of coaching arguments, since doing so now risks opening the door to exactly the kind of rebuttal testimony the vouching rules were meant to prevent.
The Lopez case is already drawing attention as a case that reshapes the balance between witness-credibility protections and trial fairness in this type of prosecution.
What follows are important excerpts from the dissent explaining the dangers of letting in so-called expert testimony to rebut the defense of coaching in Colorado sexual assault cases against children.
- I am deeply concerned about the implications of the majority’s holding on future, similarly situated defendants.
- Coaching is a common defense to allegations of sexual assault on a child, and the majority’s decision today undercuts any such defense.
- A defendant who seeks to defend against allegations of sexual assault on a child by explaining that a third party improperly induced the child’s outcry may now anticipate the introduction of expert testimony vouching for the child’s truthfulness.
Going forward, the defense must be very careful in alleging or defending a child sex assault case based on the theory that a child victim was influenced by another person and might have been told what to say—not in voir dire, opening statement, or closing argument—lest they “open the door” to expert testimony that the child told the truth.
The General Rule Regarding Allowing Expert Testimony Addressing The Credibility of Child Victims
A witness may not testify that another witness, including a child victim, told the truth on a particular occasion.
“This rule applies to both direct and indirect implications of a child’s truthfulness.” Therefore, an expert witness may not opine that a child was not coached in making allegations.
Coaching testimony is impermissible because it “constitutes conclusions about [the children’s] truthfulness in their respective interviews,” and is “tantamount to vouching for the child[ren]’s credibility.”
Summary And Conclusion – A Threat To The “Coached Victim” Defense Theory In Colorado Sex Assault Cases’
In the final analysis, the Lopez case may actually be a one-off. In the face of the extreme introduction of victim coaching by the defense in the case combined with the juror’s question seeking a normal expert application of broad principles to the case facts the Court found that under these facts:
(a) the general uncontroverted expert testimony as to coaching signs and
(b) the repeated use of the defense of the coaching theory of defense…
yhat if forensic expert Grimm’s response was excluded, the jury would not hear the full and potentially misleading picture that would permit the defense to argue that coaching was the explanation, but not permit the prosecution to present the interviewer’s trained observations of indicators of coaching.
While under the Colorado rules of evidence, a forensics expert’s testimony vouching or bolstering a witness’s credibility is prejudicial, after Lopez it may not unfairly prejudicial in context: IF the rebuttal testimony is narrowly confined (“no huge red flags,” “nothing that indicated that”) and responsive to the defense’s repeated insinuations of coaching of the witnesses.
Colorado Criminal Law – A Threat To The “Coached Victim” Defense Theory In Colorado Sex Assault Cases
The reader is alerted to the fact that Colorado criminal law, like criminal law in every state and at the Federal level, changes constantly. The article appearing above was accurate when it was drafted, but it cannot account for changes occurring after it was uploaded.
ABOUT THE AUTHOR: H. Michael Steinberg – Email The Author at: hmsteinberg@hotmail.com
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